Waterloo, Ia. – Newt Gingrich acknowledged to Iowans several times Thursday that it has been a challenging week, and he asked them to appear in a video to keep his campaign for the 2012 Republican presidential nomination alive.

He continued to deploy a sharp tongue against President Barack Obama, calling him the “food-stamp president” and saying Obama doesn’t understand the Middle East.

“I learned first of all that you have to be even more careful and even more explicit when you are a presidential candidate than when you are speaker of the House,” the former House speaker said in Ames.

Gingrich has been under fire this week after a Sunday “Meet the Press” appearance in which he called U.S. House Budget Committee Chairman Paul Ryan’s Medicare plan “too big a jump,” “right-wing social engineering” and “radical change.”

“The ad this morning is despicable,” Gingrich said. “The president should withdraw it. He should be ashamed of his national committee that he controls.”

Gingrich told reporters that he would overcome the negative press with “cheerful persistence,” which includes intense campaigning. He urged his supporters to appear in a short video attesting to their support for him because “we have to sort of convince the Washington news media that actually the voters will decide when this election is over, not five or six pundits.”

He continued: “We have a lot of people who would like to see this campaign go all the way to next year and actually talk about ideas that are sometimes confusing and actually talk about solutions.”

Gingrich again Thursday outlined several key goals, including cutting taxes, mostly for businesses. He said tax cuts would spark economic development and job creation.

“President Obama is the most successful food-stamp president in history,” Gingrich said to 120 people at the Ramada Inn Hotel and Convention Center in Waterloo. “There are 47 million Americans on food stamps. One out of every six Americans. I would like to be the most successful paycheck president.”

Waterloo resident Joan Day is a Gingrich supporter but said she didn’t believe naming Obama “the food-stamp president” was appropriate.

Gingrich told the crowd in Waterloo that Obama does not understand the Middle East, and he later told reporters that he would cut U.S. assistance to Pakistan until there were answers about how Osama bin Laden was able to hide in that country.

“We gave Pakistan $20 billion since 9/11,” Gingrich said. ” … Shouldn’t the president be asking some pretty fundamental questions” about whether bin Laden was protected by the Pakistani government?

Gingrich drew a crowd of around 100 people in Carroll on Thursday, along with about 180 in Marshalltown.

Marshalltown business owner Joe Carter asked Gingrich if he was “just really part of Washington.” Carter, a registered Republican, noted that Gingrich has spent much of his life in politics.

Gingrich, who stepped down as speaker in 1999, said he has created multiple for-profit businesses, written roughly two dozen books and produced documentaries.

“Do I know a fair amount about Washington? You betcha,” he said. “You think you’re going to send an amateur to the White House? You just did that.”